When patent owners license their patents to companies who commercialize the technology and assert the patents, the patent owner may be required to join any patent infringement lawsuit brought by the company. Specifically, if the license transfers less than all substantial rights in a patent (such as in an exclusive  field of use license), the patent owner will need to join any infringement action before that action may continue to proceed.  The same is also true when an accused infringer wishes to preemptively file a suit to have a patent declared invalid or not infringed.  Thus, even if an exclusive licensee alone makes an infringement allegation, the accused infringer may still be required to sue both the licensee and the university patent owner in its action for patent invalidity.